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Abstract In plants, light-dependent activation of de novo fatty acid synthesis (FAS) is partially mediated by acetyl-CoA carboxylase (ACCase), the first committed step for this pathway. However, it is not fully understood how plants control light-dependent FAS regulation to meet the cellular demand for acyl chains. We report here the identification of a gene family encoding for three small plastidial proteins of the envelope membrane that interact with the α-carboxyltransferase (α-CT) subunit of ACCase and participate in an original mechanism restraining FAS in the light. Light enhances the interaction between carboxyltransferase interactors (CTIs) and α-CT, which in turn attenuates carbon flux into FAS. Knockouts for CTI exhibit higher rates of FAS and marked increase in absolute triacylglycerol levels in leaves, more than 4-fold higher than in wild-type plants. Furthermore, WRINKLED1, a master transcriptional regulator of FAS, positively regulatesCTI1expression by direct binding to its promoter. This study reveals that in addition to light-dependent activation, “envelope docking” of ACCase permits fine-tuning of fatty acid supply during the plant life cycle.
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This content will become publicly available on February 1, 2026
Fatty acid desaturase 3-mediated α-linolenic acid biosynthesis in plants
Abstract Omega-3 fatty acids (ω3 FAs) are essential components of cell membranes that also serve as precursors of numerous regulatory molecules. α-Linolenic acid (ALA), one of the most important ω3 FAs in plants, is synthesized in both the plastid and extraplastidial compartments. FA desaturase 3 (FAD3) is an extraplastidial enzyme that converts linoleic acid (LA) to ALA. Phylogenetic analysis suggested that FAD3 proteins are distinct from FAD7 and FAD8 desaturases, which convert LA to ALA in plastids. Structural analysis of FAD3 proteins indicated a positive relationship between enzymatic activity and transmembrane pore length and width. An inverse relationship between temperature and ALA biosynthesis was also evident, with ALA accumulation decreasing with increasing temperature. These findings suggest that certain FAD3 enzymes are more effective at converting LA to ALA than others. This information could potentially be used to engineer crop plants with higher levels of ALA.
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- Award ID(s):
- 2131400
- PAR ID:
- 10587714
- Publisher / Repository:
- ASPB
- Date Published:
- Journal Name:
- Plant Physiology
- Volume:
- 197
- Issue:
- 2
- ISSN:
- 0032-0889
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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